Messages in this thread | | | Date | Wed, 19 Nov 2008 08:28:13 -0800 | From | Max Krasnyansky <> | Subject | Re: Using cpusets for configuration/isolation [Was Re: RT sched: cpupri_vec lock contention with def_root_domain and no load balance] |
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Gregory Haskins wrote: > Max Krasnyansky wrote: >> Nish Aravamudan wrote: >> >>> On Tue, Nov 18, 2008 at 5:59 PM, Max Krasnyansky <maxk@qualcomm.com> wrote: >>> >>>> I do not see how 'partfs' that you described would be different from >>>> 'cpusets' that we have now. Just ignore 'tasks' files in the cpusets and you >>>> already have your 'partfs'. You do _not_ have to use cpuset for assigning >>>> tasks if you do not want to. Just use them to define sets of cpus and keep >>>> all the tasks in the 'root' set. You can then explicitly pin your threads >>>> down with pthread_set_affinity(). >>>> >>> I guess you're right. It still feels a bit kludgy, but that is probably just me. >>> >>> I have wondered, though, if it makes sense to provide an "isolated" >>> file in /sys/devices/system/cpu/cpuX/ to do most of the offline >>> sequence, break sched_domains and remove a CPU from the load balancer >>> (rather than turning the load balancer off), rather than requiring a >>> user to explicitly do an offline/online. >>> >> I do not see any benefits in exposing a special 'isolated' bit and have it do >> the same thing that the cpu hotplug already does. As I explained in other >> threads cpu hotplug is a _perfect_ fit for the isolation purposes. In order to >> isolate a CPU dynamically (ie at runtime) we need to flush pending work, flush >> chaches, move tasks and timers, etc. Which is _exactly_ what cpu hotplug code >> does when it brings CPU down. There is no point in reimplementing it. >> >> btw It sounds like you misunderstood the meaning of the >> cpuset.sched_load_balance flag. It's does not turn really turn load balancer >> off, it simply causes cpus in different cpusets to be put into separate sched >> domains. In other words it already does exactly what you're asking for. >> > > On a related note, please be advised I have a bug in this area: > > http://bugzilla.kernel.org/show_bug.cgi?id=12054
Yes, I saw the original thread on this. I'll reply in there.
Max
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